Electric-arc-burning lance with or without fluid flow passageways

ABSTRACT

The lance includes an electrically conductive metal outer tube and an electrically conductive metal rod or tube inner element, which has an electrically insulating sleeve therearound, telescoped within the outer tube. A short-circuiting means is disposed between the outer tube and the inner element adjacent one end thereof. To initiate an arc between the outer tube and the inner element at one end thereof, an electric circuit is passed through the outer tube and through the inner element. The short-circuiting means shorts out the circuit causing an arc to be initiated adjacent the end of the lance between the outer tube and the inner element. Where the inner element is a tube, the electric arc initiated in accordance with the invention may be utilized to ignite oxygen or other gas flowing through the inner tube element so that the lance can be used in a manner similar to that in which an oxygen lance is used. The initiated electric arc provides the temperature necessary to bring the tip of the lance with the tubular inner element to reaction temperature for igniting the oxygen after which the power source may be disconnected. If desired, the flow of current from the power source may be maintained continuously while oxygen is flowing through the inner element of the lance so as to provide the necessary high temperature for melting through refractory and slag where the flow of burning oxygen alone would be relatively ineffective.

United States Patent [72] Inventors Kenneth H. Harvey Primary ExaminerR. F. Staubly Riverdale; AttmeyDonald S. Ferito Marshall J. McCullough, Hazel Crest, both of III. [21] A LN 348,536 ABSTRACT: The lance includes an electrically conductive [22] Filed Aug. 8,1969 metal outer tube and an electrically conductive metal rod or [45] Patented Oct. 5, 1971 tube inner element, which has an electrically insulating sleeve [73] Assignee United States Steel Cor oration therearound, telescoped within the outer tube. A short-circuiting means is disposed between the outer tube and the inner element adjacent one end thereof. To initiate an arc ELECTRIC'ARC'BURNING LANCE WITH OR between the outer tube and the inner element at one end WITlFOUT FLUIP p PASSAGEWAYS thereof, an electric circuit is passed through the outer tube 6clalmsi4nl'awmg g and through the inner element. The short-circuiting means 52 U.S.Cl 219 70, Shms out the circuit Causing arc to be initiated adjacent 219/75, 314/34 the end of the lance between the outer tube and the inner cle- Int. Cl B23k 9/24, where the inner clemem is a tube the electric are "05b 31/30 itiated in accordance with the invention may be utilized to ig- 50 Field of Search 219 70, 74, a nite Oxygen or other 2 flowing through thc inner tube 75 2 p 23 314/34 ment so that the lance can be used in a manner similar to that in which an oxygen lance is used. The initiated electric are [56] References Cited provides the temperature necessary to bring the tip of the UNITED STATES PATENTS lance with the tubular inner element to reaction temperature for i nitin the 0x en after which the ower source ma be 501 s g g Yg P y 2 3; $252 disconnected. If desired, the flow of current from the power 2472'923 6/1949 'gg l" 314/34 UX source may be maintained continuously while oxygen is flow- 3274427 9/966 Pa uette 'g 314/34 ing through the inner element of the lance so as to provide the q necessary high temperature for melting through refractory OTHER REFERENCES and slag where the flow of burning oxygen alone would be Popular ScienceMonthy, Oct. I938 pp. 193- 4 relatively ineffective.

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ELECTRIC-ARC-BURNING LANCE WITH OR WITHOUT FLUID FLOW PASSAGEWAYS The present invention relates generally to electric arc-burning equipment and more particularly has as its primary object the provision of an improved electric arc-burning lance.

It is a more specific object of the invention to provide an electric arc-burning lance which includes an outer electrically conductive metal tube; an electrically conductive metal inner element telescoped within the tube; a sleeve of electrically insulating material surrounding the element; and a short-circuiting means connected with and adjacent to one end of the tube and element whereby electric current passing through the tube and through the element is short-circuited to thereby ignite a burning arc between the tube and the element.

These and other objects will become more apparent after referring to the following specification and attached drawing, in which:

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a vertical elevational view, partly in section, of the electric arc lance of the invention;

FIG. 2 is a view similar to FIG. 1 showing a modified embodiment of the lance of the invention;

FIG. 3 is an enlarged view similar to FIG. 1 showing still another modified embodiment of the invention; and

FIG. 4 is an enlarged view similar to FIG. 2 showing yet another modified embodiment of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring more particularly to the drawing, the lance of the invention, in its preferred embodiment, consists of an elongated electrically conductive metal element 2 encased in a flexible electrically insulating sleeve 4 (such as fiberglass coated with silicon rubber) and an outer electrically conductive metal tube 6 telescoped over the insulated element 2. The inner element 2 is connected to one terminal 8 of a power source 10 while the outer tube 6 is connected to the other terminal 12 of the power source 10. Shorting means in the form of small electrically conductive metal clips 14 are provided in the outer tube 6 adjacent one end thereof extending to and contacting the inner element 2 through its insulating sleeve 4, as best shown in FIG. 1. The clips 14 are made of relatively low eletrical-resistance material.

As shown in the modified embodiment shown in FIG. 3, the short-circuiting means may consist of particles 16 of electrically conductive metal held in place by a cap 18 made of paper or other combustible material. The other elements of the modified embodiment of the invention shown in FIG. 3 are similar to those of the preferred embodiment shown in FIG. 1 and are designated by like reference characters. 7

In operation of either the lances shown in FIG. 1 or FIG. 3, the current from power source 10 that passes through the inner element 2 and the outer tube 6 is shorted out by either the clips 14 or the metal particles 16 so that a burning arc is initiated adjacent the end of the lance.

The electric arc lance of the invention will burn through metals or refractories, both conductors and nonconductors of electricity. The lance of the invention is especially suitable for use with steeland iron-producing or handling facilities such as ladles, tundishes, furnaces, etc., where oxygen contamination of the refractory nozzles and the cutting action of the oxidized slags damage the pouring nozzles of such units. The electric arc lance of the invention also eliminates oxygen contamination of the initial molten product passing through such pouring nozzles. It also eliminates the oxygen contamination of pouring tubes, nozzles and linings of degassing vessels which must be lanced repeatedly during draining after pouring operations have been completed.

Operation of the lances may be controlled by an on-otf switch 9 interposed between the power source 10 and the lance. The rate of consumption of the lance, and rate of penetration by the lance during its use may be controlled by conventional voltage and amperage controls on the power source.

FIG. 2 of the drawing illustrates another modified embodiment of the lance of the invention wherein the inner element 2' is in the form of an open-end tube adapted to conduct gases, such as oxygen. In this embodiment, the electric arc initiated in accordance with the invention is utilized to ignite the flow of oxygen through the inner element 2 and the lance is used in a manner similar to the manner in which an oxygen lance is used. A short-circuiting means used to initiate an electric are at one end of the modified lance may be in the form of clips 14' of relatively low-resistance electrically conductive metal which contact the outer tube 6' and the inner element 2 through its insulating sleeve 4 in a manner similar to that shown and described for the preferred embodiment of the invention. Altemately a metallic button (not shown) such as a spot weld could be employed to bring the outer tube 6' and the inner element 2 into electrical contact to provide a shortcircuiting means.

FIG. 4 illustrates still another modified embodiment of the lance of the invention having a tubular inner element 2", which terminates short of one end of the outer tube 6". The space between the end of the element 2" and the outer tube 6" is filled with particles 16' of electrically conductive metal held in place by a paper cap 18'. In this arrangement, a thin disc 20 of conductive metal is interposed between the end of the inner element 2" and the deposited particles of metal for the purpose of confining the metal particles to the space between the end of the inner element and the cap I8 on the end of the outer tube.

The power source connections for the embodiments of lances shown in FIGS. 2, 3 and 4 is the same as the power source connections shown in FIG. 1.

The initiated electric arc provides the temperature necessary to bring the tip of the lances shown in FIGS. 2 and 4 to reaction temperature. The power source may be disconnected by means of the off-on switch after the tip of the lance has reached reaction temperature, and the oxygen flow issuing from the tubes 2' and 2" is burning. If desired, the flow of current from the power source may be maintained continuously while oxygen is flowing through the inner elements 2' and 2" so as to provide the necessary high temperature for melting through refractory and slag where the flow of burning oxygen alone is relatively ineffective.

By use of the ignition means of the invention, where it is desired to utilize the lance as an oxygen lance, the necessity of having a workman with a welding or burning torch standing by to ignite the lance, and the inherent danger of having the combustible gases with which they operate in close proximity to molten-steel-pouring operations are both eliminated.

In applications in which oxygen is detrimental or hazardous, the lances shown in FIGS. 2 and 4 could be used with other gases, such as argon or nitrogen, to aid in removal of molten metal. In such cases, of course, current would be maintained flowing from the power source through the lance continuously.

We claim:

I. An electric arc-burning lance comprising an elongated electrically conductive metal tube, an elongated electrically conductive metal element telescoped within said tube, said tube and said element being coextensive substantially along the majority of their lengths, said element being hollow for the passage of fluid therethrough, a sleeve of non-fluid electrically insulating material surrounding said element within said tube, said tube and said element being in contact with said insulating sleeve substantially along their lengths, means connected with each of said tube and element for passing an electric current therethrough, and short-circuiting means adjacent and attached to one end of said tube and element whereby an electric current passing through said tube and element is short-circuited to thereby ignite a burning arc between said tube and said element adjacent said one end thereof.

2. An electric arc-burning lance as defined by claim I in which said short-circuiting means includes a relatively low electrically resistance metal connection extending between said tube and said element and through said insulating sleeve.

3. An electric arc-burning lance as defined by claim 2 in which said elongated electrically conductive metal element is an open-end tube adapted to conduct gases.

4. An electric arc-burning lance as defined by claim 1 in which said elongated electrically conductive metal element is an open-end tube adapted to conduct gases.

5. An electric arc-burning lance comprising an elongated electrically conductive metal tube, an elongated electrically conductive metal element telescoped within said tube, said element terminating short of one end of said tube, said elongated electrically conductive metal element being an openend tube adapted to conduct gases, a sleeve of electrically insulating material surrounding said element within said tube, means connected with each of said tube and element for passing an electric current therethrough, short-circuiting means adjacent said one end of said tube and element whereby an electric current passing through said tube and elesaid element and said one end of said tube, a thin disc of electrically conductive metal interposed between the end of said open-end tube and said deposited electrically conductive metal in particulate form, and a retaining cap of combustible material on said one end of said tube.

6. An electric arc-burning lance comprising an elongated electrically conductive metal tube, an elongated electrically conductive metal element telescoped within said tube, said element terminating short of one end of said tube, a sleeve of electrically insulating material surrounding said element within said tube, means connected with each of said tube and element for passing an electric current therethrough, shoncircuiting means adjacent one end of said tube and element whereby an electric current passing through said tube and element is short circuited to thereby ignite a burning arc between said tube and said element adjacent said one end thereof, said short-circuiting means including electrically conductive metal in particulate form deposited in said tube between the end of said element and said one end of said tube, and a retaining cap of combustible material on said one end of said tube. 

1. An electric arc-burning lance comprising an elongated electrically conductive metal tube, an elongated electrically conductive metal element telescoped within said tube, said tube and said element being coextensive substantially along the majority of their lengths, said element being hollow for the passage of fluid therethrough, a sleeve of non-fluid electrically insulating material surrounding said element within said tube, said tube and said element being in contact with said insulating sleeve substantially along their lengths, means connected with each of said tube and element for passing an electric current therethrough, and short-circuiting means adjacent and attached to one end of said tube and element whereby an electric current passing through said tube and element is short-circuited to thereby ignite a burning arc between said tube and said element adjacent said one end thereof.
 2. An electric arc-burning lance as defined by claim 1 in which said short-circuiting means includes a relatively low electrically resistance metal connection extending between said tube and said element and through said insulating sleeve.
 3. An electric arc-burning lance as defined by claim 2 in which said elongated electrically conductive metal element is an open-end tube adapted to conduct gases.
 4. An electric arc-burning lance as defined by claim 1 in which said elongated electrically conductive metal element is an open-end tube adapted to conduct gases.
 5. An electric arc-burning lance comprising an elongated electrically conductive metal tube, an elongated electrically conductive metal element telescoped within said tube, said element terminating short of one end of said tube, said elongated electrically conductive metal element being an open-end tube adapted to conduct gases, a sleeve of electrically insulating material surrounding said element within said tube, means connected with each of said tube and element for passing an electric current therethrough, short-circuiting means adjacent said one end of said tube and element whereby an electric current passing through said tube and element is short circuited to thereby ignite a burning arc between said tube and said element adjacent said one end thereof, said short-circuiting means including electrically conductive metal in particulate form deposited in said tube between the end of said element and said one end of said tube, a thin disc of electrically conductive metal interposed between the end of said open-end tube and said deposited electrically conductive metal in particulate form, and a retaining cap of combustible material on said one end of said tube.
 6. An electric arc-burning lance comprising an elongated electrically conductive metal tube, an elongated electrically conductive metal element telescoped within said tube, said element terminating short of one end of said tube, a sleeve of electrically insulating material surrounding said element within said tube, means connected with each of said tube and element for passing an electric current therethrough, short-circuiting means adjacent one end of said tube and element whereby an electric current passing through said tube and element is short circuited to thereby ignite a burning arc between said tube and said element adjacent said one end thereof, said short-circuiting means including electrically conductive metal in particulate form deposited in said tube between the end of said element and said one end of said tube, and a retaining cap of combustible material on said one end of said tube. 